The present invention relates to a print position control system in a printer including a printer head mounted on a traveling carriage and, more particularly, to a print position control system in a serial printer such as an ink jet system printer of the charge amplitude controlling type.
Generally, in a serial printer such as an ink jet system printer of the charge amplitude controlling type, a pulse signal generation means is associated with a drive mechanism of a carriage for developing a pulse signal of a given frequency in response to travel of the carriage. The thus developed pulse signal is used for controlling the print position. Generation of the pulse signal must be strictly correlated with the location of the carriage in order to ensure accurate print position control.
However, it is very difficult to strictly correlate the location of the carriage with the generation of the pulse signal especially in a printer which includes a reciprocating carriage. Deviation of the relationship between the carriage position and the pulse generation is mainly caused by a slip occurring within the drive mechanism of the carriage.
Accordingly, an object of the present invention is to provide a print position control system for a printer including a printer head mounted on a traveling carriage.
Another object of the present invention is to provide a print position control system for a serial printer, which ensures accurate print position control.
Still another object of the present invention is to provide a compensation means for compensating for the deviation of the print position in a serial printer.
Yet another object of the present invention is to simplify a drive mechanism of a carriage in a serial printer.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
To achieve the above objects, pursuant to an embodiment of the present invention, a pulse generation means is provided for developing a pulse signal in response to travel of the carriage in order to determine one character width or a print pitch.
The pulse generation means comprises a slit plate mounted on a motor shaft for developing a slit pulse signal in response to rotation of a motor which drives the carriage. A first counter means is connected to receive the slit pulse signal derived from the pulse generation means and develops a first control signal when the first counter means counts a predetermined number of pulses. The predetermined number is indicative of the one character width or the print pitch.
A detection means is associated with a guide rail of the carriage for developing a detection signal when the carriage reaches the first print position of one row in order to initiate printing of the first character. A second counter means is connected to receive the slit pulse signal and the detection signal for counting a time interval from a time at which the last pulse is developed from the pulse generation means to a time at which the detection signal is developed.
The following character printing is effected each time the first control signal is developed from the first counter means and the time interval determined by the second counter means has passed from the generation of the first control signal.